Prevalence of Dirofilaria repens in dogs in central-eastern Poland and histopathological changes caused by this infection

The aim of the study was to determine the prevalence of canine dirofilariosis in four provinces of central-eastern Poland and to describe pathological changes occurring during the course of this parasitosis. A total of 188 dogs aged from one and a half up to 16 years were examined for dirofilariosis. Blood samples were analysed for the presence of microfilariae using Knott method, as well as the method of Kingston and Morton. Pathomorphological examination of two dogs was also performed. Histological sections were stained with H&E, AB-PAS, van Gieson, and von Kossa methods. Microfilariae of Dirofilaria repens were found in blood samples of dogs that originated from the Mazowieckie, Lubelskie, and Podlaskie provinces. The mean prevalence of that species was 12.7%. Autopsy revealed the adult nematodes in the subcutaneous connective tissue. Microscopic examinations indicated the presence of microfilariae in the liver, kidneys, lungs, heart muscle, and intestines. Necrotic foci, thrombosis, and infiltrations of different intensity with eosinophils in internal organs were also observed. Significant lesions in different internal organs together with the presence of numerous microfilariae suggest their important role in the disease process.